Disk with an electrical connection element

ABSTRACT

The present invention relates to a disk with an electrical connection element, having a substrate with a first coefficient of thermal expansion, an electrically conductive structure on a region of the substrate, and a connection element with a second coefficient of thermal expansion.

The invention relates to a pane with an electrical connection elementand an economical and environmentally friendly method for itsmanufacture.

The invention further relates to a pane with an electrical connectionelement for motor vehicles with electrically conductive structures suchas, for instance, heating conductors or antenna conductors. Theelectrically conductive structures are customarily connected to theon-board electrical system via soldered-on electrical connectionelements. Due to different coefficients of thermal expansion of thematerials used, mechanical stresses occur that strain the panes and cancause breakage of the pane during manufacture and operation.

Lead-containing solders have high ductility that can compensate themechanical stresses occurring between an electrical connection elementand the pane by plastic deformation. However, because of the End of LifeVehicles Directive 2000/53/EC, lead-containing solders have to bereplaced by lead-free solders within the EC. The directive is referredto, in summary, by the acronym ELV (End of Life Vehicles). The objectiveis to ban extremely problematic components from products resulting fromthe massive increase in disposable electronics. The substances affectedare lead, mercury, cadmium, and chromium. This relates, among otherthings, to the implementation of lead-free soldering materials inelectrical applications on glass and the introduction of correspondingreplacement products.

EP 1 942 703 A2 discloses an electrical connection element on panes ofmotor vehicles, wherein the difference in the coefficient of thermalexpansion of the pane and the electrical connection element is <5×10⁻⁶/°C. In order to enable adequate mechanical stability and processability,it is proposed to use an excess of solder material. The excess of soldermaterial flows out from the intermediate space between the connectionelement and the electrically conductive structure. The excess of soldermaterial causes high mechanical stresses in the glass pane. Thesemechanical stresses ultimately result in breakage of the pane.

The object of the present invention is to provide a pane with anelectrical connection element and an economical and environmentallyfriendly method for its manufacture, whereby critical mechanicalstresses in the pane are avoided.

The object of the present invention is accomplished through a pane witha connection element that comprises the following characteristics:

-   -   a substrate made of glass (1) with a first coefficient of        thermal expansion,    -   an electrically conductive structure (2) with a layer thickness        of 5 μm to 40 μm, preferably 5 μm to 20 μm, on a region of the        substrate (1),    -   a connection element (3) with a second coefficient of thermal        expansion, whereby the difference between the first and the        second coefficient of expansion is ≧5×10⁻⁶/° C., and    -   a layer of a soldering material (4), which electrically connects        the connection element (3) to subregions of the electrically        conductive structure (2).

An electrically conductive structure is applied on the pane. Anelectrical connection element is electrically connected by a solderingmaterial on subregions to the electrically conductive structure. Thesolder material flows out with an outflow width of <1 mm from theintermediate space between the connection element and the electricallyconductive structure.

In a preferred embodiment, the maximum outflow width is preferably lessthan 0.5 mm and, in particular, roughly 0 mm. The maximum outflow widthcan even be negative, i.e., pulled back into the intermediate spaceformed by an electrical connection element and an electricallyconductive structure, preferably in a concave meniscus.

The maximum outflow width is defined as the distance between the outeredges of the connection element and the point of the solder materialcrossover, at which the solder material drops below a layer thickness of50 μm.

The advantage resides in the reduction of mechanical stresses in thepane, in particular, in the critical region present with a large soldermaterial crossover.

The first coefficient of thermal expansion is preferably from 8×10⁻⁶/°C. to 9×10⁻⁶/° C. The substrate is preferably glass that has,preferably, a coefficient of thermal expansion from 8.3×10⁻⁶/° C. to9×10⁻⁶/° C. in a temperature range from 0° C. to 300° C.

The second coefficient of thermal expansion is preferably from 8×10⁻⁶/°C. to 9×10⁻⁶/° C., particularly preferably from 8.3×10⁻⁶/° C. to9×10⁻⁶/° C. in a temperature range from 0° C. to 300° C.

The coefficient of thermal expansion of the connection element can be≦4×10⁻⁶/° C.

The electrically conductive structure according to the invention has,preferably, a layer thickness of 8 μm to 15 μm, particularly preferablyfrom 10 μm to 12 μm. The electrically conductive structure according tothe invention contains, preferably, silver, particularly preferablysilver particles and glass frits.

The layer thickness of the solder according to the invention is<3.0×10⁻⁴ m. The solder material according to the invention contains,preferably, tin and bismuth, indium, zinc, copper, silver, orcompositions thereof. The proportion of tin in the solder compositionaccording to the invention is from 3 wt.-% to 99.5 wt.-%, preferablyfrom 10 wt.-% to 95.5 wt.-%, particularly preferably from 15 wt.-% to 60wt.-%. The proportion of bismuth, indium, zinc, copper, silver, orcompositions thereof in the solder composition according to theinvention is from 0.5 wt.-% to 97 wt.-%, preferably 10 wt.-% to 67wt.-%, whereby the proportion of bismuth, indium, zinc, copper, orsilver can be 0 wt.-%. The solder composition according to the inventioncan contain nickel, germanium, aluminum, or phosphorus at a proportionof 0 wt.-% to 5 wt.-%. The solder composition according to the inventioncontains, very particularly preferably, Bi40Sn57Ag3, Sn40Bi57Ag3,Bi59Sn40Ag1, Bi57Sn42Ag1, In97Ag3, Sn95.5Ag3.8Cu0.7, Bi67In33,Bi33In50Sn17, Sn77.2In20Ag2.8, Sn95Ag4Cu1, SN99Cu1, Sn96.5Ag3.5, ormixtures thereof.

The connection element according to the invention contains preferably atleast 50 wt.-% to 75 wt.-% iron, 25 wt.-% to 50 wt.-% nickel, 0 wt.-% to20 wt.-% cobalt, 0 wt.-% to 1.5 wt.-% magnesium, 0 wt.-% to 1 wt.-%silicon, 0 wt.-% to 1 wt.-% carbon, or 0 wt.-% to 1 wt.-% manganese.

The connection element according to the invention contains preferablychromium, niobium, aluminum, vanadium, tungsten, and titanium at aproportion of 0 wt.-% to 1 wt.-%, molybdenum at a proportion of 0 wt.-%to 5 wt.-%, as well as production-related admixtures.

The connection element according to the invention contains preferably atleast 55 wt.-% to 70 wt.-% iron, 30 wt.-% to 45 wt.-% nickel, 0 wt.-% to5 wt.-% cobalt, 0 wt.-% to 1 wt.-% magnesium, 0 wt.-% to 1 wt.-%silicon, or 0 wt.-% to 1 wt.-% carbon.

The connection element according to the invention further containspreferably at least 50 wt.-% to 60 wt.-% iron, 25 wt.-% to 35 wt.-%nickel, 15 wt.-% to 20 wt.-% cobalt, 0 wt.-% to 0.5 wt.-% silicon, 0wt.-% to 0.1 wt.-% carbon, or 0 wt.-% to 0.5 wt.-% manganese.

The connection element according to the invention is coated,particularly preferably, with nickel, tin, copper and/or silver. Theconnection element according to the invention is coated, veryparticularly preferably, with 0.1 μm to 0.3 μm nickel and/or 3 μm to 10μm silver. The connection element can be plated with nickel, tin,copper, and/or silver. Ni and Ag improve the current carrying capacityand corrosion stability of the connection element and the wetting withthe solder material.

The connection element according to the invention contains preferablykovar (FeCoNi) and/or invar (FeNi) with a coefficient of thermalexpansion of invar from 0.1×10⁻⁶/° C. to 4×10⁻⁶/° C. or a maximumdifference of kovar of 5×10⁻⁶/° C. from the coefficient of expansion ofthe pane.

Kovar is an iron-nickel-cobalt alloy that has a coefficient of thermalexpansion of usually roughly 5×10⁻⁶/° C., which is thus less than thecoefficient of typical metals. The composition contains, for example, 54wt.-% iron, 29 wt.-% nickel, and 17 wt.-% cobalt. In the area ofmicroelectronic and microsystem technology, kovar is, consequently, usedas a housing material or as a submount. Submounts lie, according to thesandwich principle, between the actual substrate material and thematerial with, for the most part, a clearly higher coefficient ofexpansion. Kovar thus serves as a compensating element which absorbs andreduces the thermo-mechanical stresses caused by the differentcoefficients of thermal expansion of the other materials. Similarly,kovar is used for metal-glass implementations of electronic components,material transitions in vacuum chambers.

Invar is an iron-nickel alloy with a content of 36 wt.-% nickel(FeNi36). There is a group of alloys and compounds that have theproperty of having abnormally small or sometimes negative coefficientsof thermal expansion in certain temperature ranges. Fe65Ni35 invarcontains 65 wt.-% iron and 35 wt.-% nickel. Up to 1 wt.-% magnesium,silicon, and carbon are usually alloyed to change the mechanicalproperties. By alloying 5 wt.-% cobalt, the coefficient of thermalexpansion α can be further reduced. One name for the alloy is Inovco,FeNi33Co4.5 with an coefficient of expansion α (20° C. to 100° C.) of0.55×10⁻⁶/° C.

If an alloy such as invar with a very low absolute coefficient ofthermal expansion of <4×10⁶/° C. is used, overcompensation of mechanicalstresses occurs by noncritical pressure stresses in the glass or bynoncritical tensile stresses in the alloy. Because of theovercompensation of the alloy, the outflow width from the intermediatespace between the connection element and the electrically conductivestructure is negligible.

Kovar and/or invar can also be welded, crimped, or glued as acompensation plate on a connection element made, for example, of steel,aluminum, titanium, copper. As a bimetal, favorable expansion behaviorof the connection element relative to the glass expansion can beobtained. The compensation plate is preferably hat-shaped.

The electrical connection element contains, on the surface facing thesolder material, a coating that contains copper, zinc, tin, silver,gold, or a combination thereof, preferably silver. This prevents aspreading of the solder material out beyond the coating and limits theoutflow width.

The electrical connection element can be designed in the form of abridge with at least two contact surfaces, but also as a connectionelement with one contact surface.

The connection elements are, in the plan view, for example, preferably 1mm to 50 mm long and wide and, particularly preferably 3 mm to 30 mmlong and wide and, very particularly preferably 2 mm to 4 mm wide and 12mm to 24 mm long.

The shape of the electrical connection element can form solder depots inthe intermediate space of the connection element and the electricallyconductive structure. The solder depots and wetting properties of thesolder on the connection element prevent the outflow of the soldermaterial from the intermediate space. The solder depots can berectangular, rounded, or polygonal in design.

The distribution of the soldering heat and, thus, the distribution ofthe solder material during the soldering process can be defined by theshape of the connection element. Solder material flows to the warmestpoint. For example, the bridge can have a single or double hat shape inorder to distribute the heat advantageously in the connection elementduring the soldering process.

The introduction of the energy during the electrical connecting of anelectrical connection and an electrically conductive structure occurspreferably by means of punches, thermodes, piston soldering, preferablylaser soldering, hot air soldering, induction soldering, resistancesoldering, and/or with ultrasound.

The object of the invention is further accomplished through a method ofmanufacture of a pane with a connection element, wherein

a) solder material is arranged and applied on the connection element asa platelet with a fixed layer thickness, volume, shape, and arrangement,b) an electrically conductive structure is applied to a substrate,c) the connection element with the solder material is arranged on theelectrically conductive structure, andd) the connection element is soldered with the electrically conductivestructure.

The solder material is preferably applied in advance to the connectionelements, preferably as a platelet with a fixed layer thickness, volume,shape, and arrangement on the connection element.

The connection element is welded or crimped to a sheet, braided wire,mesh (not shown) made, for example, of copper and connected to theon-board electrical system (also not shown).

The connection element is preferably used in heated panes or in paneswith antennas in buildings, in particular, in automobiles, railroads,aircraft, or watercraft. The connection element serves to connect theconducting structures of the pane to electrical systems that arearranged outside the pane. The electrical systems are amplifiers,control units, or voltage sources.

The invention is explained in detail with reference to drawings andexemplary embodiments. They depict:

FIG. 1 a perspective view of a first embodiment of the pane according tothe invention,

FIG. 2 a cross-section A-A through the pane of FIG. 1,

FIG. 3 a cross-section through an alternative pane according to theinvention,

FIG. 4 a cross-section through another alternative pane according to theinvention,

FIG. 5 a cross-section through another alternative pane according to theinvention,

FIG. 6 a perspective view of an alternative embodiment of the paneaccording to the invention,

FIG. 7 a cross-section B-B through the pane of FIG. 6, and

FIG. 8 a detailed flow chart of the method according to the invention.

FIG. 1 and FIG. 2 show, in each case, a detail of a heatable pane 1according to the invention in the region of the electrical connectionelement 3. The pane 1 was a 3-mm-thick thermally prestressed single-panesafety glass made of soda lime glass. The pane 1 had a width of 150 cmand a height of 80 cm. An electrically conductive structure 2 in theform of a heating conductor structure 2 was printed on the pane 1. Theelectrically conductive structure 2 contained silver particles and glassfrits. In the edge region of the pane 1, the electrically conductivestructure 2 was widened to a width of 10 mm and formed a contact surfacefor the electrical connection element 3. In the edge region of the pane1, there was also a covering serigraph (not shown). In the region of thecontact surface between the electrical connection element 3 and theelectrically conductive structure 2, solder material 4 was applied,which effected a durable electrical and mechanical connection betweenthe electrical connection element 3 and the electrically conductivestructure 2. The solder material 4 contained 57 wt.-% bismuth, 42 wt.-%tin, and 1 wt.-% silver. The solder material 4 was arranged through apredefined volume and shape completely between the electrical connectionelement 3 and the electrically conductive structure 2. The soldermaterial 4 had a thickness of 250 μm. An outflow of the solder material4 from the intermediate space between the electrical connection element3 and the electrically conductive structure 2, which exceeds a layerthickness t of 50 μm, was observed to a maximum outflow width of b=0.5mm. The electrical connection element 3 was an alloy that contained 65wt.-% iron and 35 wt.-% nickel. The electrical connection element 3 wasdesigned in the form of the bridge and had a width of 4 mm and a lengthof 24 mm. The material thickness of the connection element 3 was 0.8 mm.The contact surface of the connection element 3 had a width of 4 mm anda length of 4 mm. No critical mechanical stresses were observed in thepane 1 due to the arrangement of the solder material 4, predefined bythe connection element 3 and the electrically conductive structure 2.The connection of the pane 1 to the electrical connection element 3 viathe electrically conductive structure 2 was durably stable.

FIG. 3 depicts, in continuation of the exemplary embodiment of FIGS. 1and 2, an alternative embodiment of the connection element 3 accordingto the invention. The electrical connection element 3 was provided onthe surface facing the solder material 4 with a silver-containingcoating 5. This prevented spreading of the solder material out beyondthe coating 5 and limited the outflow width b. The outflow width b ofthe solder material 4 was less than 1 mm. No critical mechanicalstresses were observed in the pane 1 due to the arrangement of thesolder material 4. The connection of the pane 1 to the electricalconnection element 3 via the electrically conductive structure 2 wasdurably stable.

FIG. 4 depicts, in continuation of the exemplary embodiment of FIGS. 1and 2, another alternative embodiment of the connection element 3according to the invention. The electrical connection element 3contained, on the surface facing the solder material 4, a recess with adepth of 250 μm that formed a solder depot for the solder material 4. Itwas possible to completely prevent outflow of the solder material 4 fromthe intermediate space. The thermal stresses in the pane 1 werenoncritical and a durable electrical and mechanical connection wasprovided between the connection element 3 and the pane 1 via theelectrically conductive structure 2.

FIG. 5 depicts, in continuation of the exemplary embodiment of FIGS. 1and 2, another alternative embodiment of the connection element 3according to the invention. The electrical connection element 3 was bentupward on the edge regions. The height of the upward bend of the edgeregion of the glass pane 1 was a maximum of 400 μm. This formed a spacefor the solder material 4. The predefined solder material 4 formed aconcave meniscus between the electrical connection element 3 and theelectrically conductive structure 2. It was possible to completelyprevent outflow of solder material 4 from the intermediate space. Theoutflow width b, at roughly 0, was less than zero, largely because ofthe meniscus formed. The thermal stresses in the pane 1 werenoncritical, and a durable electrical and mechanical connection wasprovided between the connection element 3 and the pane 1 via theelectrically conductive structure 2.

FIG. 6 and FIG. 7 depict another embodiment of the pane 1 according tothe invention with connection element 3 in the form of a bridge. Theconnection element 3 contained an iron-containing alloy with acoefficient of thermal expansion of 8×10⁻⁶/° C. The material thicknesswas 2 mm. In the region of the contact surface of the connection element3 with the pane 1, hat-shaped compensation members 6 were applied withan iron-nickel-cobalt alloy. The maximum layer thickness of thehat-shaped compensation members 6 was 4 mm. By means of the compensationmembers, it was possible to adapt the coefficient of thermal expansionof the connection element 3 to the requirements of the pane 1 and of thesolder material 4. The hat-shaped compensation members 6 resulted inimproved heat flow during the production of the solder connection 4. Theheating occurred primarily in the center of the contact surface. It waspossible to further reduce the outflow width b of the solder material 4.Because of the low outflow width b of <1 mm and the adapted coefficientof expansion, it was possible to further reduce the thermal stresses inthe pane 1. The thermal stresses in the pane 1 were noncritical, and adurable electrical and mechanical connection was provided between theconnection element 3 and the pane 1 via the electrically conductivestructure 2.

FIG. 8 depicts in detail a method according to the invention formanufacture of a pane 1 with an electrical connection element 3. Anexample of the method according to the invention for manufacture of apane with an electrical connection element 3 is presented there. As thefirst step, it was necessary to portion the solder material 4 accordingto shape and volume. The portioned solder material 4 was arranged on theelectrical connection element 3. The electrical connection element 3 wasarranged with the solder material 3 on the electrically conductivestructure 2. A durable connection of the electrical connection element 3to the electrically conductive structure 2 and, thus, to the pane 1 tookplace through the input of energy.

EXAMPLE

Test specimens were produced with the pane 1 (thickness 3 mm, width 150cm, and height 80 cm), the electrically conductive structure 2 in theform of a heating conductor structure, the electrical connection element3, the silver layer on the contact surfaces of the connection element 3,and the solder material 4. The solder material 4 was applied in advanceas a platelet with fixed layer thickness, volume, and shape on thecontact surface of the connection element 3. The connection element 3was applied with the solder material applied on the electricallyconductive structure 2. The connection element was soldered onto theelectrically conductive structure 2 at a temperature of 200° C. and aprocessing time of 2 seconds. Outflow of the solder material 4 from theintermediate space between the electrical connection element 3 and theelectrically conductive structure 2, which exceeded a layer thickness tof 50 μm, was observed only to a maximum outflow width of b=0.5 mm. Thedimensions and compositions of the electrically conductive structure 2,the electrical connection element 3, the silver layer on the contactsurfaces of the connection element 3, and the solder material 4 arefound in Table 1 and FIGS. 1 and 2 and the description of the figures.

With all specimens, it was possible to observe, with a temperaturedifference from +80° C. to −30° C., that no glass substrate 1 broke orshowed damage. It was possible to demonstrate that, shortly aftersoldering, these panes 1 with the soldered connection element 3 werestable against a sudden temperature drop.

TABLE 1 Components Material Example Connection Iron (wt.-%) 65 elementNickel (wt.-%) 35 CTE (coefficient of thermal 1.7 expansion) × 10⁻⁶ (0°C.-100° C.) Difference between CTE of the 6.6 connection element andsubstrate × 10⁻⁶/° C. (0° C.-100° C.) Thickness of the connection  8.0 ×10⁻⁴ element (m) Solderable Silver (wt.-%) 100 layer Thickness of thelayer (m)  7.0 × 10⁻⁶ Solder layer Tin (wt.-%) 42 Bismuth (wt.-%) 57Silver (wt.-%) 1 Thickness of the solder 250 × 10⁻⁶ layer in (m) Thethickness of the solderable 255 × 10⁻⁶ layer and the solder layer (m)Glass substrate CTE × 10⁻⁶ (0° C.-320° C.) 8.3 (Soda lime glass)

In addition, test specimens were executed with a second composition ofthe electrical connection element 3. The dimensions and compositions ofthe electrically conductive structure 2, the electrical connectionelement 3, the silver layer on the contact surfaces of the connectionelement 3, and the solder material 4 detailed values are found in Table2. Here as well, it was possible to observe that, with a temperaturedifference from +80° C. to −30° C., no glass substrate 1 broke or showeddamage. It was possible to demonstrate that, shortly after soldering,these panes 1 with the soldered connection element 3 were stable againsta sudden temperature drop.

TABLE 2 Components Material Example Connection Iron (wt.-%) 54 elementNickel (wt.-%) 29 Cobalt (wt.-%) 17 CTE (coefficient of thermal 5.1expansion) × 10⁻⁶ (0° C.-100° C.) Difference between CTE of the 3.2connection element and substrate × 10⁻⁶/° C. (0° C.-100° C.) Thicknessof the connection  8.0 × 10⁻⁴ element (m) Solderable Silver (wt.-%) 100layer Thickness of the layer (m)  7.0 × 10⁻⁶ Solder layer Tin (wt.-%) 40Bismuth (wt.-%) 57 Silver (wt.-%) 3 Thickness of the solder 250 × 10⁻⁶layer in (m) The thickness of the solderable 255 × 10⁻⁶ layer and thesolder layer (m) Glass substrate CTE × 10⁻⁶ (0° C.-320° C.) 8.3 (Sodalime glass)

In addition, test specimens were executed with a second composition ofthe electrical connection element 3 and a second composition of thesolder material 4. The dimensions and compositions of the electricallyconductive structure 2, the electrical connection element 3, the silverlayer on the contact surfaces of the connection element 3, and thesolder material 4 detailed values are found in Table 3. Here as well, itwas possible to observe that, with a temperature difference from +80° C.to −30° C., no glass substrate 1 broke or showed damage. It was possibleto demonstrate that, shortly after soldering, these panes 1 with thesoldered connection element 3 were stable against a sudden temperaturedrop.

TABLE 3 Components Material Example Connection Iron (wt.-%) 65 elementNickel (wt.-%) 35 CTE (coefficient of thermal 1.7 expansion) × 10⁻⁶ (0°C.-100° C.) Difference between CTE of the 6.6 connection element andsubstrate × 10⁻⁶/° C. (0° C.-100° C.) Thickness of the connection  8.0 ×10⁻⁴ element (m) Solderable Silver (wt.-%) 100 layer Thickness of thelayer (m)  7.0 × 10⁻⁶ Solder layer Tin (wt.-%) 40 Bismuth (wt.-%) 57Silver (wt.-%) 3 Thickness of the solder 250 × 10⁻⁶ layer in (m) Thethickness of the solderable 255 × 10⁻⁶ layer and the solder layer (m)Glass substrate CTE × 10⁻⁶ (0° C.-320° C.) 8.3 (Soda lime glass)

Comparative Example 1

The comparative example 1 was carried out the same as the example withthe following differences. The dimensions and components of theelectrically conductive structure 2, the electrical connection element3, the metal layer on the contact surfaces of the connection element 3,and the solder material 4 are found in Table 4. The solder material 4was, in accordance with the prior art, not applied in advance as aplatelet on the contact surface of the connection element 3. Theconnection element 3 was soldered to the electrically conductivestructure 2 in accordance with the conventional method. With the outflowof the solder material 4 from the intermediate space between theelectrical connection element 3 and the electrically conductivestructure 2, which exceeded a layer thickness t of 50 μm, an averageoutflow width b=2 mm to 3 mm was obtained.

With a sudden temperature difference from +80° C. to −30° C., it wasobserved that the glass substrates 1 had major damage shortly aftersoldering.

TABLE 4 Comparative Components Material Example 1 Connection Titanium(wt.-%) 100 element CTE (coefficient of thermal 8.80 expansion) × 10⁻⁶(0° C.-100° C.) Difference between CTE of the 0.5 connection element andsubstrate × 10⁻⁶/° C. (0° C.-100° C.) Thickness of the connection   8.0× 10⁻⁴ element (m) Solderable Silver (wt.-%) 100 layer Thickness of thelayer (m)   7.0 × 10⁻⁶ Solder layer Tin (wt.-%) 48 Bismuth (wt.-%) 46Silver (wt.-%) 2 Copper(wt.-%) 4 Thickness of the solder 50-200 × 10⁻⁶layer in (m) The thickness of the solderable 55-205 × 10⁻⁶ layer and thesolder layer (m) Glass substrate CTE × 10⁻⁶ (0° C.-320° C.) 8.3 (Sodalime glass)

Comparative Example 2

The comparative example 2 was carried out the same as the example withthe following differences. The dimensions and components of theelectrically conductive structure 2, the electrical connection element3, the metal layer on the contact surfaces of the connection element 3,and the solder material 4 are found in Table 5. The solder material 4was, in accordance with the prior art, not applied in advance as aplatelet on the contact surface of the connection element 3. Theconnection element 3 was soldered to the electrically conductivestructure 2 in accordance with the conventional method. With the outflowof the solder material 4 from the intermediate space between theelectrical connection element 3 and the electrically conductivestructure 2, which exceeded a layer thickness t of 50 μm, an averageoutflow width b=1 mm to 1.5 mm was obtained.

With a sudden temperature difference from +80° C. to −30° C., it wasobserved that the glass substrates 1 had major damage shortly aftersoldering.

TABLE 5 Comparative Components Material Example 2 Connection Copper(wt.-%) 100 element CTE (coefficient of thermal 16 expansion) × 10⁻⁶ (0°C.-100° C.) Difference between CTE of the 7.7 connection element andsubstrate × 10⁻⁶/° C. (0° C.-100° C.) Thickness of the connection   8.0× 10⁻⁴ element (m) Solderable Silver (wt.-%) 100 layer Thickness of thelayer (m)   7.0 × 10⁻⁶ Solder layer Tin (wt.-%) 71.5 Indium (wt.-%) 24Silver (wt.-%) 2.5 Bismuth (wt.-%) 1.5 Copper (wt.-%) 0.5 Thickness ofthe solder 50-200 × 10⁻⁶ layer in (m) The thickness of the solderable55-205 × 10⁻⁶ layer and the solder layer (m) Glass substrate CTE × 10⁻⁶(0° C.-320° C.) 8.3 (Soda lime glass)

It was demonstrated that panes according to the invention with glasssubstrates 1 and electrical connection elements 3 according to theinvention have better stability against sudden temperature differences.This result was unexpected and surprising for the person skilled in theart.

LIST OF REFERENCE CHARACTERS

-   -   (1) Pane/glass    -   (2) Electrically conductive structure/Ag-screenprint    -   (3) Electrical connection element/Fe—Ni alloy kovar    -   (4) Solder material (Bi40Sn57Ag3)    -   (5) Wetting layer/Ag-coating    -   (6) Compensation member    -   b Maximum outflow width of the solder material    -   t Limiting thickness of the solder material    -   A-A′ Section line    -   B-B′ Section line

1. A pane, comprising: a substrate made of glass having a firstcoefficient of thermal expansion, an electrically conductive structurewith a layer thickness of 5 μm to 40 μm on a region of the substrate; aconnection element having a second coefficient of thermal expansion,wherein the difference between the first coefficient of expansion andthe second coefficient of expansion is ≧5×10⁻⁶/° C.; and a layer of asolder material electrically connecting the connection element tosubregions of the electrically conductive structure.
 2. The paneaccording to claim 1, wherein the second coefficient of thermalexpansion is ≦4×10⁻⁶/° C.
 3. The pane according to claim 1, wherein amaximum outflow width b in an intermediate space formed by theconnection element and the electrically conductive structure is pulledback into a concave meniscus.
 4. The pane according to claim 1, whereinthe electrically conductive structure has a layer thickness of 8 μm to15 μm.
 5. The pane according to claim 1, wherein the electricallyconductive structure comprises silver.
 6. The pane according to claim 1,wherein the layer thickness of the solder material is <3.0×10⁻⁴.
 7. Thepane according to claim 1, wherein the solder material contains elementsselected from the group consisting of: tin and bismuth, indium, zinc,copper, silver, or compositions thereof.
 8. The pane according to claim7, wherein the proportion of tin in the solder material is 3 wt.-% to99.5 wt.-%.
 9. The pane according to claim 7, wherein a proportion ofbismuth, indium, zinc, copper, silver, or compositions thereof in thesolder material is 0.5 wt.-% to 97 wt.-%.
 10. The pane according toclaim 1, wherein the connection element comprises at least 50 wt.-% to75 wt.-% iron, 25 wt.-% to 50 wt.-% nickel, 0 wt.-% to 20 wt.-% cobalt,0 wt.-% to 1.5 wt.-% magnesium, 0 wt.-% to 1 wt.-% silicon, 0 wt.-% to 1wt.-% carbon, or 0 wt.-% to 1 wt.-% manganese.
 11. The pane according toclaim 10, wherein the connection element comprises at least 55 wt.-% to70 wt.-% iron, 30 wt.-% to 45 wt.-% nickel, 0 wt.-% to 5 wt.-% cobalt, 0wt.-% to 1 wt.-% magnesium, 0 wt.-% to 1 wt.-% silicon, or 0 wt.-% to 1wt.-%.
 12. The pane according to claim 1, wherein the connection elementis coated with nickel, tin, copper, and/or silver.
 13. The paneaccording to claim 12, wherein the connection element is coated with 0.1μm to 0.3 μm nickel and/or 3 μm to 10 μm silver.
 14. A method forproduction of a pane with an electrical connection element, the methodcomprising: arranging and applying a solder material on the connectionelement as a platelet with a fixed layer thickness, volume, shape, andarrangement; applying an electrically conductive structure a substrate;arranging the connection element with a solder material on theelectrically conductive structure; and soldering the connection elementto the electrically conductive structure.
 15. A method comprising: usingthe pane with an electrical connection element according to claim 1, formotor vehicles with electrically conductive structures.
 16. The paneaccording to claim 1, further comprising a coating containing betweenthe layer of solder material and the connection element, wherein thecoating containing silver prevents the solder material from spreading tothe connection element.
 17. The pane according to claim 1, wherein theconnection element has a recessed portion on a side facing theelectrically conductive structure, the recessed portion adapted tocontain the solder material and prevent outflow of the solder material.18. The pane according to claim 1, wherein edge regions of theconnection element are bent upward, the solder material being formed ina space formed between the bent edge regions and the electricallyconductive structure.
 19. A method comprising: using the pane with anelectric connection element according to claim 1 with heating conductorsand/or antenna conductors.